Osteoporosis

Osteoporosis is a disease characterised by low bone mass and deterioration of bone strength. Fragile bones are more prone to fracture. Common fractures include wrist, arm, leg and ribs, as well as the hips and spine. Osteoporosis is often called “the silent thief” because bone loss occurs without symptoms. Individuals may not know they have osteoporosis until their bones are so weak that a strain, bump or fall causes a fracture. In Australia, two in three women, and one in three men over the age of 60 will suffer an osteoporotic fracture in their remaining lifetime. Currently over 2.2 million Australians are affected by the disease. Osteoporotic problems cost the Australian community more than $1 billion per year in direct costs. The total cost, which includes factors such as carers and lost income, is estimated to be $7 billion per year (or $20 million every day). Aside from these financial costs, fractures often affect mobility, lead to loss of confidence and quality of life, and increase the risk of dying prematurely.

What causes osteoporosis?

Our bones grow in size and in strength and density as our bodies develop through childhood and adolescence. Bone mass reaches its maximum density at around 25 years of age and then drops off slowly thereafter. Achieving a lower peak bone mass puts individuals at greater risk in later life, even with normal rates of bone loss. Although osteoporosis usually occurs in older people, it can be seen in children and young adults. Adverse lifestyle habits such as smoking, excessive drinking or unhealthy diet from as early as the teenage years may influence peak bone mass. This may cause lower bone density in later years. As the bone mineral amount falls, the fragility of the bones progressively increases and so does the risk of fractures. Most osteoporotic fractures occur before age 75.

How is it diagnosed?

Osteoporotic fractures are generally diagnosed by x-rays. However, a painless bone density test is much more effective as it allows osteoporosis to be detected before fractures occur, and treatment can commence without delay. These tests are widely available at virtually all major hospitals and medical centres.

What are the risk factors and can I prevent it?

The factors that increase your likelihood of developing osteoporosis are:

Gender – you are more likely to develop osteoporosis if you are female, however one in three fractures occur in men

Post-menopause – the loss of oestrogen after menopause is a major risk factor

Family history of osteoporosis – inherited factors account for a major part of an individuals risk of having the disease

Limited physical activity and inadequate dietary calcium intake

Limited exposure to sunlight resulting in low vitamin D intake

Cigarette smoking and excessive alcohol intake

Prolonged use of certain medications such as high dose cortisone

Some diseases including hyperparathyroidism and intestinal malabsorption

Prevention is an important part of any health strategy. Eat a balanced diet rich in calcium and vitamin D. It is considered prudent to exercise at least three times a week, ideally weight-bearing exercise (e.g. running, skipping, weights). Do not smoke. Reduce youralcohol intake. It is also useful to have bone density tests after the age of 60, depending on the values observed.

What if I already have osteoporosis?

There are treatments available for osteoporosis that increase and maintain bone density and provide supplements for any missing key elements involved in bone strength. These include:

Hormone therapy (HT) largely prevents bone loss in post menopausal women and can reduce fracture risk, but has potential adverse effects that should be discussed with your doctor

Vitamin D supplements are particularly important, especially for people who are housebound or have very little exposure to the sun

Appropriate medications for fracture pain management

What research is Garvan doing in this area?

Garvan’s Osteoporosis and Bone Biology division combines clinical, molecular and cellular research to explore the links between genetic, hormonal and lifestyle influences on the achievement of optimum bone mass. In our molecular research, scientists have discovered that the brain hormones leptin and neuropeptide Y have different effects on bone formation, which could lead to the identification of new treatments. Most recently, genetic markers have been identified that indicate lower risk of osteoporotic fractures. Identifying genetic factors such as these provides a starting point for genetic testing for osteoporosis, and importantly identifies novel targets for potential therapies.

Our research draws on the Dubbo Osteoporosis Epidemiology Study (DOES). Started in 1989, DOES is the world’s longest running large-scale epidemiological study of osteoporotic fractures in men and women. This study involves over 3500 participants in the NSW regional centre of Dubbo and aims to identify health and lifestyle factors that contribute to improvement or deterioration of our bones. In addition to this population study, Garvan is also conducting a genetic study with over 400 members of large extended families, in order to pinpoint genes important to bone health.

Results from DOES recently identified that, contrary to popular belief, osteoporosis is not just a woman’s disease. While women are initially twice as likely as men to have a fracture, once the first break occurs, the risk of a second fracture substantially increases to the point where there is no differentiation between men and women in the high risk of having another fracture. Garvan scientists have found that measurements of bone density loss can improve the accuracy of fracture risk assessment and could help identify who would benefit the most from preventative medications. We are now developing a selection model for doctors to identify, at an early stage, people who have a high risk of fracture. These patients are the ones who could most benefit from preventative therapies. The selection model includes simple tests of postural ability which, in conjunction with bone mineral density measurements, could be used to predict fracture risk.